Electronic display device and display control method

ABSTRACT

An electronic display device includes measurement sensors that measure respective items, a digital display that displays the items, and a processor. The processor determines a main image related to a measurement of at least one of the items and updates a screen at first timing. Upon displaying the main image related to a measurement of an item other than the first item on the digital display, the processor determines that a sub image is related to measurement of the first item, synchronizes the first timing with update timing that is related to the main image, and simultaneously updates the main image and the sub image.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2019-056212, filed on Mar. 25,2019, the entire contents of which are incorporated herein by reference.

BACKGROUND

The technical field relates to an electronic display device and adisplay control method.

There are electronic display devices that are capable of digitallydisplaying a plurality of measurement values. The measurement valuesinclude those related to time such as the current time, elapsed time,and remaining setting time of a timer, and those related to spatialphysical quantities such as atmospheric pressure, direction, tilt angle,and the like.

Depending on the measurement situation, a plurality of measurementvalues may be desired to be visually recognized at the same time. JPh7-55964 A discloses a technique of displaying altitude based onbarometric pressure measurement and elapsed time based on measurementwith a stopwatch in parallel on one screen.

SUMMARY

According to an aspect of the present invention, there is provided anelectronic display device, including:

measurement sensors that measure respective items;

a digital display that displays the items; and

a processor that determines a main image related to a measurement of atleast one of the items and updates a screen at first timing, wherein,

upon displaying the main image related to a measurement of an item otherthan the first item on the digital display, the processor determinesthat a sub image is related to measurement of the first item,synchronizes the first timing with update timing that is related to themain image, and simultaneously updates the main image and the sub image.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended as a definition of the limitsof the invention but illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention, wherein:

FIG. 1 is a front view of an electronic timepiece;

FIG. 2 is a block diagram showing functional configuration of theelectronic timepiece;

FIGS. 3A, 3B, and 3C are diagrams each showing an example of a displayscreen related to a stopwatch function;

FIGS. 4A and 4B are diagrams each showing an example of a display screenrelated to a stopwatch function; and

FIG. 5 is a flowchart of control procedures in a display update controlprocess.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, one or more embodiments will be described on the basis ofthe drawings.

FIG. 1 is a front view of an electronic timepiece 1 as an electronicdisplay device of this embodiment.

The electronic timepiece 1 includes a case 11, a display screen 12, pushbutton switches B1 to B4, a crown C1, and the like. The upper portion ofthe display screen 12 maybe covered with a windshield glass or the like.

The case 11 has, for example, a cylindrical shape with both sidesopened, and the display screen 12 is provided at one of the sides, andthe other side is sealed with a lid (not shown). A substrate, chip,sensor, electronic component, battery, and the like having configurationfor various operations are located inside the case 11 between thedisplay screen 12 and the lid.

The display screen 12 is a digital display screen of a dot matrix type.In this embodiment, in the display screen 12 can be displayed not onlynumerals and symbols related to the current time, but variouscharacters, a drawing(s) indicating a charge state of the battery, andthe like. A font, arrangement, and the like can be individually set andchanged in each screen.

The push button switches B1 to B4 and the crown C1 penetrate the case 11outward from the inside where these components are each positioned, soas to accept respective external operations by a user or the like. Eachof the push button switches B1 to B4 outputs, as an input signal, anelectric signal corresponding to a pressing operation. The crown C1outputs, as an input signal, electric signals each corresponding to apull-out/push-in operation and a rotation operation.

FIG. 2 is a block diagram showing functional configuration of theelectronic timepiece 1.

The electronic timepiece 1 includes a CPU (Central Processing Unit) 41(processor), a memory 42, an oscillator circuit 45, a frequency dividingcircuit 46, a clock circuit 47 (time counter), an operation receiver 51,a display 52, a measurement sensor 53, a power supply unit 60, and thelike.

The CPU 41 is a processor that performs various types of arithmeticprocessing, and integrally controls operations of each component of theelectronic timepiece 1. The CPU 41 reads and executes programs 421stored in the memory 42, thereby performing various control operations.The CPU 41 can switch the contents displayed on the display screen 12based on the operation content received by the operation receiver 51,and can start, pause, stop, and finish various measurements. Thecontents to be measured include, in addition to those measured by eachsensor of the measurement sensor 53 described later, elapsed time basedon the stopwatch function, and remaining time until the set periodelapses (or until the set time) based on the timer function. Thestopwatch function and the timer function are collectively referred toas a time measurement function.

The memory 42 provides the CPU 41 with a memory space for work, andstores various kinds of data. The CPU 41 includes, for example, a RAM(Random Access Memory) and a nonvolatile memory. The RAM is used by theCPU 41 to perform the arithmetic processing, and stores temporary data.The nonvolatile memory is a flash memory, for example, and storesvarious settings, programs 421, and the like.

The memory 42 stores measurement history information 422. Themeasurement history information 422 includes a measurement resultobtained by the measurement sensor 53. For example, the informationduring the measurement may be stored in the RAM, and then stored in thenonvolatile memory after completion of the measurement.

The oscillation circuit 45 generates a clock signal having apredetermined oscillation frequency, for example, 32.768 kHz, andoutputs the clock signal to the frequency dividing circuit 46. Thefrequency dividing circuit 46 performs frequency division of the clocksignal input from the oscillator circuit 45 to convert the clock signalinto a signal of a frequency that is necessary for each component of theelectronic timepiece 1 to operate, and outputs the converted signal. Thesignal generated by the frequency dividing circuit 46 is output to theclock circuit 47 and the like. In the elapsed time measurement based onthe stopwatch function and the like, the high frequency signal outputfrom the frequency dividing circuit 46 is counted, for example, in theunit of 1/100 second or the like. A time measurement sensor of thisembodiment includes the frequency dividing circuit 46 and the CPU 41.

The clock circuit 47 processes a signal of a predetermined frequencythat is input from the frequency dividing circuit 46, and obtains andholds the current date and time. The format of the date and time held bythe clock circuit 47 is not limited to a format represented by year,month, day, hour, minute, and second, but may be an appropriate formatsuitably processed by the CPU 41 and the like. Because the oscillationfrequency of the oscillation circuit 45 slightly changes depending onthe external environment such as a temperature, the date and timeobtained by the clock circuit 47 in a normal environment may have anerror (clock drift) of 0.5 seconds in a day at the maximum, for example.The electronic timepiece 1 may be provided with a communication unitand/or a radio wave receiving unit (not shown) to obtain an accuratedate and time from the outside, so as to correct for the error in thedate and time obtained by the clock circuit 47.

The operation receiver 51 receives an input operation by a user fromoutside, and outputs input signals corresponding to the input operationto the CPU 41. In this embodiment, the operation receiver 51 has theabove-described push button switches B1 to B4, crown C1, and the like.The operation receiver 51 may have a touchscreen overlaid with thedisplay screen of the display 52.

The display 52 performs a display operation based on the control of theCPU 41, that is, a digital display operation on the display screen 12.The display screen 12 is of a dot matrix type as described above, inwhich a memory type liquid crystal can maintain a content once displayedthereon without frequent update maintenance operations (refreshing). Inthis embodiment, the display screen 12 has a display with amemory-in-pixel (MIP) liquid crystal.

The measurement sensor 53 measures a physical quantity of apredetermined item, and outputs measurement results (measurement values)to the CPU 41. The measured physical quantity includes at least one ofan atmosphere, orientation (magnetic north), acceleration, andgravitational direction (gravitational acceleration), for example. Themeasurement sensor 53 has sensors corresponding to the respective itemsto be measured. Measurement values of a physical quantity of the item tobe measured are obtained regularly (at predetermined time intervals inmany cases), and are corrected or converted into values to be displayedas needed. The correction and conversion maybe performed by themeasurement sensor 53 or may be performed by the CPU 41. Table data forcorrection and/or conversion may be stored in the memory 42. The contentof the display related to the measurement is not necessarily themeasurement value itself, but may be the value corrected and/orconverted as described above.

The CPU 41, the frequency dividing circuit 46, the clock circuit 47, andthe measurement sensor 53 are included in the measurement sensor of thisembodiment. The measurement sensor as a whole can measure a plurality ofitems including the date and time, amount of time measured based on thestopwatch function, and the like.

The power supply unit 60 supplies power at a predetermined operatingvoltage from the battery 61 to each unit of the electronic timepiece 1(maybe indirectly via the CPU 41 or the like). The battery 61 includes,for example, a solar panel and a storage cell. The battery 61 may be aremovable dry cell, a button cell, or the like. Alternatively, thebattery 61 may be a secondary cell such as a lithium ion cell, that ischarged using a predetermined cable or via a connection terminal. Thepower supply unit 60 can measure the output voltage of the battery 61,and regularly outputs the measurement value to the CPU 41. The CPU 41can estimate the remaining power of the battery 61 based on themeasurement value.

Hereinafter, the display operation according to this embodiment will bedescribed. In the electronic timepiece 1 of this embodiment, as shown inFIG. 1, the current time is usually displayed as a first item andupdated every second (at first timing). During a measurement of eachitem other than a measurement of the current time (the first item), thescreen related to the measurement and the current time screen aredisplayed simultaneously and in parallel. When a plurality of screensare updated in parallel in this way, the screen related to onemeasurement is set as “a main image” and the screen related to the othermeasurement is set as “a sub image” in the electronic timepiece 1. Themain image may be displayed more largely than the sub image, forexample, or may be colored to be emphasized, and the like.

FIG. 3A, FIG. 3B, FIG. 3C, FIG. 4A and FIG. 4B each show an example thedisplay screen 12 including a screen based on the stopwatch function.

FIG. 3A shows an example of the display screen 12 before start of themeasurement or in a state where the measurement result has been resetafter completion of the measurement. In FIG. 3A, the notation of“STOPWATCH” shows the function mode, the numerals of “0”, “00”, and “00”in the center respectively shows the hour, minute, and second of theinitial measurement time, and the numerals “5” and “53” in the lowerportion (below the screen of the measurement time) respectively showsthe hour and minute of the current time.

Furthermore, the character and symbol “'” respectively represent thehour and minute of the measurement time, and the symbol “:” is displayedbetween the numerals indicating the hour and the minute of the currenttime. A battery indicator representing the charge state of the batteryis displayed between the measurement time and the current time. Thesymbol “:” blinks (repeats appearing for one second and disappearing forone second alternately) at the exact start timing of each second of thecurrent time, and thus represents elapse of the time. When a value ofminute or more changes, the displayed numeral is also updated. Because aclocking operation is not performed (stopped) in FIG. 3A, the screen ofthe measurement time is the sub image. Therefore, the screen related tothe current time is the main image, and the screen related to theelapsed time is set to be the sub image. In the screen related to thecurrent time, which is the main image, the symbol “:” blinks everyminute in real time, and the value of minute or more is updated when thevalue of second is zero.

FIG. 3B and FIG. 3C each show an example of the display screen 12including a screen during the measurement of the elapsed time. When theelapsed time measurement is started, the elapsed time screen is updatedevery time when the elapsed time increases by one second (referred to asan update time unit that is shorter than a display time unit describedlater). At the same time, the symbol “'” may be turned on and off(appear and disappear) every second. During the measurement of theelapsed time (during display related to the measurement(s) other thanthe current time), in many cases, the measurement time (display relatedto the measurement other than the current time) is more important forthe user than the current time. Therefore, it is determined that thescreen of the measurement time is the main image, and the screen of thecurrent time is the sub image. In such cases, the measurement time isdisplayed in real time. That is, the elapsed time screen is updated atthe exact start timing of each second of the elapsed time. Numeralsindicating the unit of minute or more are updated at zero second inevery minute (the display time unit).

In the screen of the current time as a sub image, the display of thesymbol “:” and switching of the numeral(s) of the minute value or moreare each synchronized with the update timing of the elapsed time screenas the main image. That is, the main image and sub image are updatedsimultaneously. The actual start timing of each second of the currenttime is usually different from the start timing of each second of theelapsed time based on the stopwatch function. Therefore, the updatetiming of the current time screen is slightly different from the actualstart timing of each second of the current time. The update timing ofthe current time screen is delayed by less than one second whensynchronized with the subsequent update timing of the elapsed timescreen, and the update timing of the current time screen has an error inthe range of ±0.5 seconds when synchronized with the nearest updatetiming of the elapsed time screen. The mark “P” in the drawingsindicates that it is currently in the afternoon. Alternatively, theupdate timing of the current time screen may be synchronized with thelatest update timing of the elapsed time screen and brought forward byless than one second, such that a problem does not occur due to thedelay in the update. The symbols “:” and “'” (predetermined marks)simultaneously appear (FIG. 3B) and then simultaneously disappear (FIG.3C) (perform a blinking operation).

When the split time or the lap time is measured based on the stopwatchfunction, the update of the screen is temporarily paused for the elapsedtime which is an item during the measurement. In such a case, a mark“SPL” is displayed as shown in FIG. 4A and FIG. 4B, for example, torepresent that the split time is now displayed. Furthermore,continuation of the elapsed time measurement is represented by thesymbol “'” blinking every second (disappearing in FIG. 4B) during thecontinuation. In such a situation, the “current time” that is beingmeasured and displayed is switched to the main image, and the “elapsedtime” to the sub image. That is, the current time screen is updated inreal time, and the blinking of the symbol “'” in the elapsed time screenis synchronized with the exact start of every second of the currenttime. In this case, the update timing of the elapsed time screen (thatis, the blinking timing of the symbol “'”) is delayed by less than onesecond or has an error in the range of ±0.5 seconds.

Each of the symbols “:” and “'” appears and disappears at odd secondsand at even seconds. Depending on the correspondence between the valueof a second in the current time and the value of a second in the elapsedtime, the symbols “:” and “'” may appear and disappear simultaneously ormay appear alternately. Alternatively, regardless of the correspondence,the symbols may appear/disappear simultaneously.

The operations and display in the measurement of the remaining timebased on a timer function are equivalent to those in the measurement ofthe elapsed time based on the above-mentioned stopwatch function. Themeasurement related not to time but to a spatial physical quantity issometimes performed equal to or more than once a second, and the screenis desired to be updated immediately after the measurement (a longresponse time is desired to be avoided). For example, the updatefrequency may be more than once a second when the main image may not bethe current time screen but a screen of a compass based on a result of amagnetic field measurement. The more the update frequency is, the lessthe degree of improvement in efficiency related to the display operationis. Therefore, an upper limit of the update frequency (for example, 10times or less per second) may be determined depending on the requiredefficiency.

FIG. 5 is a flowchart showing control procedures by the CPU 41 in adisplay update control process performed in the electronic timepiece 1of this embodiment. This display update control process is performedaccording to the display control method of this embodiment, and iscontinuously performed from activation of the electronic timepiece 1 aslong as the display state is maintained.

When the display update control process is started, the CPU 41determines whether or not a measurement other than time counting is inprogress (step S101). During the above-described reset state, thestandby state of one second or more in the measurement intervals, or thelike, it is not determined that the measurement other than the timecounting is in step S101. If it is determined that the measurement otherthan time counting is not in progress (“NO” in step S101), the CPU 41then proceeds to step S111.

If it is determined that the measurement other than time counting is inprogress (“YES” in step S101), the CPU 41 determines whether or not thecontent during the measurement is being displayed (step S102). In stepS102, the content during the measurement and determined to be displayeddoes not include the content for which the measurement has beencompleted, such as the split time and the lap time described above. Thecontent during the measurement and determined to be displayed includesthe display of each measurement result that is measured or acquiredcontinuously or discretely at intervals of one second or less.

If it is determined that the content during the measurement is not beingdisplayed (“NO” instep S102), the CPU 41 then proceeds to step S111. Ifit is determined that the content during the measurement is displayed(“YES” in step S102), the CPU 41 determines whether or not it is time toupdate the screen related to the measurement other than time counting(step S103). If it is determined that it is not time to update thescreen (“NO” in step S103), the CPU 41 returns to step S101. If it isdetermined that it is time to update the screen (“YES” in step S103),the CPU 41 generates display data and outputs, to the display 52, acommand to update the screen using the generated display data (stepS104). As described above, the display data is obtained by synchronizingdisplaying of the current time screen and displaying of the screen ofthe measurement other than time counting. When the generated displaydata is the same as the previous display data, the display data is notnecessarily output to the display 52. The processes of steps S101, S103and S104 constitute an updating control step in the display controlmethod of this embodiment. The CPU 41 then returns to step S101.

When proceeding from step S101 or S102 to step S111, the CPU 41determines whether or not it is time to update the current time screen(step S111). If it is determined that it is not time to update thecurrent time screen (“NO” in step S111), the CPU 41 returns to stepS101. If it is determined that it is time to update the current timescreen (“YES” in step S111), the CPU 41 proceeds to step S104. Theprocesses of steps S111 and S104 constitute an update step in thedisplay control method of this embodiment.

As described above, the electronic timepiece 1 which is the electronicdisplay device of this embodiment has the measurement sensors (themeasurement sensor 53, the frequency dividing circuit 46, and the clockcircuit 47) capable of measuring a plurality of items, the display 52that is a digital display, and the CPU 41 that determines that a screenrelated to a measurement of at least one first item (in many cases, atleast the current time) among the plurality of items to be displayed onthe display 52 is the main image and then updates the screen everysecond. When displaying a main image related to the measurement of anitem other than the first item (current time) on the display 52, the CPU41 determines that the screen related to the measurement of the firstitem is the sub image and synchronizes the update timing of the subimage (first timing) with the update timing of the main image. As aresult, in the electronic timepiece 1, the main image is updated at thesame time as the sub image.

As described above, when all the screens are updated at the updatetiming determined for the main image, it is possible to reduce powerconsumption and processing load by the less update frequency and tocause the electronic timepiece 1 to efficiently perform the displayoperation.

Furthermore, the measurement sensor has the clock circuit 47 thatobtains the current time as the first item to be measured, and it isdetermined that the current time screen is the sub image while a screenrelated to a measurement other than time counting is displayed.

That is, when a user has started the measurement and displaying of ascreen related to a measurement item(s) other than the current time, theinformation on the current time may be necessary but is not likely to beas important as the information on the measurement item(s) other thanthe current time. Therefore, a time lag of about less than one secondhardly causes a problem to the user. As a result, when the update timingof the current time screen is synchronized with that of the screenrelated to the other measurement item(s), it is possible to reduceoccurrence of a problem or a sense of discomfort due to the display andto perform more efficient display, thereby improving user-friendliness.

The measurement is performed at an interval of one second or less (equalto or more than once a second) for the item as the main image. That is,the frequency of the measurement and update of the main image issufficient as compared with that of the measurement and update of thecurrent time screen. Therefore, even though displayed and updated insynchronization with the update timing of the main image, the currenttime can be displayed with a sufficiently small time lag, as small asthe counting error of a generally-used clock circuit 47. As a result, itis possible to improve the efficiency of the display operation whileoccurrence of a problem due to the time lag of displaying can besuppressed.

Furthermore, the measurement sensor has the CPU 41 and the frequencydividing circuit 46 as a time measurement sensor that measures theelapsed time as an item to be measured. The CPU 41 determines that theelapsed time screen is the main image during measurement of the elapsedtime based on the outputs from the frequency dividing circuit 46, anddetermines that the elapsed time screen is the sub image during stoppingof measurement of the elapsed time. That is, even in the display screenrelated to a function for measuring the elapsed time (for example, thestopwatch function or timer function), the screen of the elapsed time orthe remaining time of the timer is the sub image while the measurementis not performed, so that the screen (s) related to other measurement(s) can be appropriately displayed in real time without a time lag.Because a user frequently stares at the elapsed time screen and therebyhas a problem or feels a sense of discomfort due to the time lag relatedto the elapsed time screen, the elapsed time screen may bepreferentially the main image during the measurement of the elapsedtime. With flexible determination in this way, the display operation canbe more efficient as appropriate.

Furthermore, the CPU 41 updates spelled-out numerals in each of theelapsed time screen and the current time screen every minute, and causeseach of the symbol “:” and the symbol “'” to blink more frequently, thatis, every second. The spelled-out numerals are updated less frequentlythan the blinking symbols in such a case. When update of the elapsedtime screen is synchronized with update of the current time screen, thedisplay operation can be performed more efficiently without causingdiscomfort for the user. In particular, since the symbols are not oftenused for purposes other than indicating that the measurement is beingperformed, there is almost no problem even though the blinking does notsynchronize with the timing corresponding to the measured data.

When pausing update of the screen related to an item as the main imageduring the measurement of the item, the CPU 41 switches the screenrelated to the item during the measurement to the sub image. That is,even during the measurement of an item displayed as the main image, theCPU 41 may switch the main image and the sub image temporarily ordisplay the progress. For example, the screen related to the item duringthe measurement (that is, the screen showing the progress) may beswitched to the sub image, which results in displaying of the screenrelated to the item during the measurement not in real time. Thisimproves real-time properties and decreases the time lag of the screendepending on the actual display conditions and thereby user convenience.

Furthermore, according to the display control method including theupdate control step of synchronizing the update timing of a plurality ofmeasurements as described above, it is possible to reduce the updatefrequency without causing a serious problem related to the display. Thisreduces power consumption, reduces processing load, and improvesefficiency in the display operation.

The present invention is not limited to the above embodiment, and can bevariously modified.

For example, in the above embodiment, the current time screen and thescreen(s) of other measurement(s) (for example, the elapsed time screen)are displayed in combination, but the present invention is not limitedto this. The update timing can also be synchronized with the main imagewhen multiple screens each related to the elapsed time are displayed incombination, one elapsed time screen based on the stop watch functionand a remaining-time screen based on the timer function are displayed incombination, an elapsed-time screen and a screen related to themeasurement of another space physical quantity are displayed incombination, or the like. In such cases, the update of the screenrelated to the spatial physical quantity measurement may be synchronizedwith the update of the current time screen or the main image that may bethe elapsed time screen or the remaining-time screen. That is, thespatial physical quantity measurement may be controlled so as not to bethe item for the main image but to be included in the plurality of thefirst items together with the current time.

The value of the minute is spelled out but the value of the second isnot spelled out in the above embodiment, however, the value of thesecond may be spelled out. Alternatively, the value of the second may bespelled out and displayed only in the main image. That is, only thenumeral that changes at each update timing may be explicitly displayed.The update interval related to the main image is not limited to be onesecond or less, but may be longer than one second as long as there is nosignificant problem in visual recognition of the sub image. Themeasurement used as the main image may be selected depending on thedisplay update frequency required for the sub image.

In the above embodiment, the current time screen is switched to the mainimage during measurement of an item that is not being displayed in realtime, for example, during displaying of the split time or the lap time.However, such switching may not be always performed. For example, if itis determined that real time display is always paused for a short time,such switching may not be made.

In the above embodiment, the current time is always displayed as the subimage during measurement and displaying related to an item(s) other thanthe current time. However, the current time may be continued to bedisplayed as the main image when the measurement and displaying relatesto a spatial physical quantity or the like, which leads to no problemeven when displayed with a delay of about one second after themeasurement. Alternatively, while the current time screen is the subimage so that the mark “:” therein blinks with a time lag, the currenttime screen may be temporarily switched from the sub image to the mainimage every minute so that the spelled out numerals related to theminute value and the like therein can be updated without a time lag.

The blinking mark is not limited to the symbol “:” or “'” but may be adifferent blinking symbol or mark (for example, a mark having a circleshape or triangle shape) at the same position as or different positionfrom the position of the symbol “:” or “'”. Instead of a simply blinkingmark, for example, a mark may change its own positions alternately ormay move around in a predetermined cycle.

When a user desires to update a screen in real time regarding a contentnot frequently measured or changing, the screen may be updated at anyarbitrary time whether it is the main image or the sub image.

In the above embodiment, one of the two screens related to respectivemeasurements is the main image, and the other is the sub image. Whenthere are three or more screens related to respective measurements, itmay be determined that one is the main image, and all the others are thesub images. In such a case, priority levels may be determined for therespective measurements, and, among the screens each related to an itemduring the measurement and display, the screen corresponding to thehighest priority level may be determined as the main image.Alternatively, the three or more screens may include two or more mainimages, and all the screens may be updated every time when the contentrelated to any of the main images changes. The efficiency of the displayoperation can be improved as the display update related to thecontent(s) set as the sub image(s) is synchronized with the update ofthe main images.

Other than the memory-type liquid crystal display screen of the aboveembodiment, a display screen having a memory function of displaycontents may be used, for example, a display screen of anelectrophoretic type used for electronic paper. When the display screenis not of a memory-type, the update timing of the sub image issynchronized with that of the main image so that the frequency ofgenerating display data can be reduced. As a result, the load ofprocessing related to generation of the image data can be reduced.

Although the electronic timepiece is described as an example in theabove embodiment, the present invention is not limited thereto, butincludes an electronic display device as long as it can display aplurality of screens related to respective measurements in parallel. Forexample, it may be an activity display device that displays elapsedtime, number of walking steps, altitude, and the like in parallel.

Besides, the specific details of the components, control contents,display contents, display procedures, and the like described in theabove embodiments can be appropriately modified without departing fromthe scope of the present invention.

Although several embodiments of the present invention have beendescribed, the scope of the present invention is not limited to theabove described embodiments and includes the scope of the presentinvention that is described in the claims and the equivalents thereof.

What is claimed is:
 1. An electronic display device, comprising:measurement sensors that measure respective items; a digital displaythat displays the items; and a processor that determines a main imagerelated to a measurement of at least one of the items and updates themain image at first timing, wherein, upon displaying the main imagerelated to a measurement of an item other than the first item on thedigital display, the processor determines that a sub image is related toa measurement of the first item, synchronizes the first timing withupdate timing that is related to the main image, for simultaneouslyupdates the main image and the sub image.
 2. The electronic displaydevice according to claim 1, wherein the measurement sensors include atime counter that measures a current time as the first item, and, upondisplaying a screen related to a measurement not by the time counter, ascreen of the current time is the sub image.
 3. The electronic displaydevice according to claim 2, wherein an item corresponding to the mainimage is measured equal to or more than once a second.
 4. The electronicdisplay device according to claim 1, wherein the measurement sensorsinclude a time measurement sensor that measures elapsed time as one ofthe items, upon measuring the elapsed time by the time measurementsensor, the processor determines that a screen related to the elapsedtime is the main image, and upon stopping a measurement of the elapsedtime, the processor determines that a screen related to the elapsed timeis the sub image.
 5. The electronic display device according to claim 2,wherein the measurement sensors include a time measurement sensor thatmeasures elapsed time as one of the items, upon measuring the elapsedtime by the time measurement sensor, the processor determines that ascreen related to the elapsed time is the main image, and upon stoppinga measurement of the elapsed time, the processor determines that ascreen related to the elapsed time is the sub image.
 6. The electronicdisplay device according to claim 3, wherein the measurement sensorsinclude a time measurement sensor that measures elapsed time as one ofthe items, upon measuring the elapsed time by the time measurementsensor, the processor determines that a screen related to the elapsedtime is the main image, and upon stopping a measurement of the elapsedtime, the processor determines that a screen related to the elapsed timeis the sub image.
 7. The electronic display device according to claim 2,wherein the measurement sensors include a time measurement sensor thatmeasures elapsed time as one of the items, and the processor updates ascreen of the elapsed time and a screen of the current time each at apredetermined display time unit, and causes a predetermined mark toappear and disappear each for a predetermined update time unit that isshorter than the display time unit.
 8. The electronic display deviceaccording to claim 3, wherein the measurement sensors include a timemeasurement sensor that measures elapsed time as one of the items, andthe processor updates a screen of the elapsed time and a screen of thecurrent time each at a predetermined display time unit, and causes apredetermined mark to appear and disappear each for a predeterminedupdate time unit that is shorter than the display time unit.
 9. Theelectronic display device according to claim 7, wherein the display timeunit is one minute and the update time unit is one second.
 10. Theelectronic display device according to claim 8, wherein the display timeunit is one minute and the update time unit is one second.
 11. Theelectronic display device according to claim 1, wherein, upon stoppingupdate of a screen that is related to an item during a measurement andthat is the main image, the processor switches a screen related to theitem during the measurement to the sub image.
 12. The electronic displaydevice according to claim 2, wherein, upon stopping update of a screenthat is related to an item during a measurement and that is the mainimage, the processor switches a screen related to the item during themeasurement to the sub image.
 13. The electronic display deviceaccording to claim 3, wherein, upon stopping update of a screen that isrelated to an item during a measurement and that is the main image, theprocessor switches a screen related to the item during the measurementto the sub image.
 14. The electronic display device according to claim4, wherein, upon stopping update of a screen that is related to an itemduring a measurement and that is the main image, the processor switchesa screen related to the item during the measurement to the sub image.15. The electronic display device according to claim 5, wherein, uponstopping update of a screen that is related to an item during ameasurement and that is the main image, the processor switches a screenrelated to the item during the measurement to the sub image.
 16. Theelectronic display device according to claim 6, wherein, upon stoppingupdate of a screen that is related to an item during a measurement andthat is the main image, the processor switches a screen related to theitem during the measurement to the sub image.
 17. The electronic displaydevice according to claim 7, wherein, upon stopping update of a screenthat is related to an item during a measurement and that is the mainimage, the processor switches a screen related to the item during themeasurement to the sub image.
 18. The electronic display deviceaccording to claim 8, wherein, upon stopping update of a screen that isrelated to an item during a measurement and that is the main image, theprocessor switches a screen related to the item during the measurementto the sub image.
 19. The electronic display device according to claim9, wherein, upon stopping update of a screen that is related to an itemduring a measurement and that is the main image, the processor switchesa screen related to the item during the measurement to the sub image.20. A display control method of displaying, on a digital display,screens each related to respective items measured by measurementsensors, the method comprising: determining a main image related to ameasurement of at least one of the items and updating a screen at firsttiming; and update controlling including, upon displaying the main imagerelated to a measurement of an item other than the first item on thedigital display, determining that a sub image is related to ameasurement of the first item, synchronizing the first timing withupdate timing that is related to the main image, and simultaneouslyupdating the main image and the sub image.